The present invention relates generally to molded articles and, more particularly, to molded articles laminated with a heat insulating sheet member and a process for producing such molded articles.
An example of a molded article having a heat insulating sheet member, such as cloth, which is laminated to the outer surface of the article in the molding process is disclosed in Japanese Patent Laid-Open Publication No. 57-185120. This molded article is produced by a blow molding process in which a fiber sheet is placed on the outer surface of the mold.
A molded article which has a heat insulating sheet member, such as cloth, laminated to the outer surface thereof has a beautiful appearance and superb feel, which are important characteristics of a successful commercial product. It is difficult, however, to produce such an article integrally by means of a blow molding process because of problems associated with cooling of the molded article.
In general, there are two types of blow molding processes. In the first type the heat of the parison, i.e., the molten material to be subjected to blow molding, is externally removed by means of a mold. In the second type the heat of the parison is internally removed by blowing air inside the wall of the molded article. The most effective method for cooling the molded article is external cooling in which the wall of the molded article is cooled by means of a mold. In the case where a molded hollow article has a heat insulating sheet member, such as cloth, laminated to the outer surface thereof, however, a longer period of time is required for cooling because the heat insulating sheet member interposed between the molded article and the mold impedes the transfer of heat from the molded article to the mold. As a result, the molding cycle is rendered inefficient. If a molded article having such a laminate is released from a mold after the same period of time as for a molded article without such a laminate, then such molded article is not sufficiently cooled before the mold is opened. This insufficient cooling causes shrinkage-induced deformation of the molded article to occur on standing after the molded article is released from the mold. Shrinkage-induced deformation is especially problematic when the heat insulating sheet member is formed on one side of the molded article. In this case, the wall onto which the heat insulating sheet member is laminated shrinks on standing after release from the mold due to insufficient cooling, whereas the wall or walls without a heat insulating sheet member laminated thereto do not shrink on standing after release from the mold because they have been sufficiently cooled in the mold. The shrinkage differential between the wall onto which the heat insulating sheet member is laminated and the wall or walls without a heat insulating sheet member laminated thereto causes deformation to occur in the molded article.
In view of the foregoing, what is needed is a molded article having a heat insulating sheet member laminated thereto which can be sufficiently cooled by means of the mold within the mold cycle for a molded article without such a laminate, as well as a process for producing such a molded article.